\begin{tabular}{l*{6}{c}}
\toprule
                    &\multicolumn{1}{c}{1963-1987}&\multicolumn{1}{c}{1963-2016}&\multicolumn{1}{c}{1963-1987}&\multicolumn{3}{c}{1963-2016}         \\\cmidrule(lr){2-2}\cmidrule(lr){3-3}\cmidrule(lr){4-4}\cmidrule(lr){5-7}
                    &\multicolumn{1}{c}{(1)}&\multicolumn{1}{c}{(2)}&\multicolumn{1}{c}{(3)}&\multicolumn{1}{c}{(4)}&\multicolumn{1}{c}{(5)}&\multicolumn{1}{c}{(6)}\\
\midrule
Relative supply of college workers&      -1.166&      -0.388&      -1.059&      -0.584&      -0.724&      -0.745\\
                    &     (0.302)&     (0.055)&     (0.243)&     (0.063)&     (0.085)&     (0.118)\\
\addlinespace
Real minimum wage   &            &            &      -0.236&      -0.207&      -0.158&      -0.171\\
                    &            &            &     (0.094)&     (0.044)&     (0.054)&     (0.060)\\
\addlinespace
Time                &       0.045&       0.017&       0.040&       0.022&            &            \\
                    &     (0.011)&     (0.001)&     (0.009)&     (0.002)&            &            \\
\addlinespace
Constant            &      -0.021&       0.018&      -0.003&       0.024&       0.009&       0.002\\
                    &     (0.021)&     (0.008)&     (0.021)&     (0.008)&     (0.012)&     (0.022)\\
\midrule
Time Polynomial     &           1&           1&           1&           1&           2&           3\\
Observations        &          25&          54&          25&          54&          54&          54\\
\textit{R}-squared  &       0.048&       0.948&       0.328&       0.967&       0.966&       0.965\\
\bottomrule
\end{tabular}
